Denmark: 1,000 Megawatts Of Offshore Wind, And No Signs of Slowing Down

On March 18, Dong Energy’s Anholt offshore wind farm connected its 36thSiemens 3.6 megawatt (MW) turbine to the electric grid, thereby bringing the total of Denmark's connected offshore wind to 1 gigawatt (1,000 megawatts). This capacity covers the equivalent of about 1 million Danish households' electricity consumption. The Anholt complex itself will include 400 megawatts of capacity when completed. And Denmark has no plans to stop there, recently announcing that it will invite bids for an additional 1,500 MW of offshore wind. Denmark now gets almost 25% of its electricity from windpower, and this country of 5.5 million in habitants is planning to double that number to 50% by 2020.

It won’t be an easy task. With the existing wind capacity, there have already been times in recent years when surpluses have been generated and Denmark has actually paid other countries to take the excess power supply (much like the situation in West Texas, where surpluses of wind occasionally result in negative pricing for short periods). If significant changes to the electric system are not made, it is possible that supply might eclipse demand for up to 1000 hours per year by 2020 (out of the 8760 hours in a year), according to Jen Moller Birkebaek, a vice president at Energinet.dk, quoted in the NY Times.

In order for the integration of wind energy to effectively occur with minimal disruption, a number of existing tools must continue to be used, while new ones are developed. One critically important element used today is hydro storage capacity in neighboring Norway (which is supplied by 99% hydro) and Sweden (over 50% hydro), supported by robust interconnection transmission lines. When excess wind energy is generated, power is often transmitted to these neighboring countries. In turn, they simply throttle back their hydro plants and store more water behind dams for later use. When more electricity is needed, power can flow the other way. In this sense, Norway and Sweden’s hydro systems serve as large batteries in a larger interconnected system.

A key domestic tool on the demand side -with the potential for soaking up huge surpluses - is increased use of electricity to heat water in the country’s extensive district heating systems. Research suggests that up between 20 and 30 gigawatt-hours (GWh) of electric energy could be stored as useful heat in hot water. If this technology is adopted when wind prices are low or even potentially negative, it can supplant the need for fossil fuel-based heating. It is estimated that 30 GWh of heat storage would provide enough absorptive capacity for 5 GW of installed wind capacity. This electric heating technology is already in play in a number of the district heating loops served by combined heat and power plants, with the development of enormous insulated water tanks.

Electric vehicles may play a key role as well, as high capacity batteries could ultimately serve to provide regulating capacity, absorbing or supply power back to the grid to flatten out some of the intermittency associated with windpower. Partly for this reason, Better Place, a company that creates electric car charging networks, has focused heavily on the Danish market. In December of last year, Better Place completed Europe’s first nationwide electric car network with 1400 operational charge points (and has switched over 10,000 batteries between June and December of 2012). Meanwhile, Clever, a Danish company in the EV charging space announced in late 2012 that it was installing 50 fast charging stations (capable of recharging a vehicle in 15-20 minutes) by mid-2013. However, Denmark recently downgraded by 50% its initial 2020 goal for electric cars, from 400,000 to 200,000, so this resource may not prove to be as significant as initially expected.

More traditional tools will be also be required. Western Denmark currently has an AC connector to Germany for exports of 1500 MW and imports of 950 MW of power. It also has 740 MW, and 1040 MW of DC interconnections with Sweden, and Norway respectively. Meanwhile, the eastern part of the country has a 600 MW DC connector to Germany and 1900 MW AC line to Sweden. Despite these connections, most experts believe that for the government to meet its goal of 50% wind, it will need to invest in more robust interconnections with other countries, including the Netherlands and perhaps even the UK.

And gas-fired generation will also likely play a role, as it can be quickly ramped up and down in response to the vicissitudes of wind. For this to happen, gas generation would need to be paid a higher rate than is traditionally the case, since it would be primarily used in a back-up role. Capital costs would by definition have to be recouped over fewer kilowatt-hours of generation, so some tariff revision to allow for higher prices would likely be necessary.

Improving wind forecasting capabilities will also help smooth the integration. Energinet.dk - the Danish Power Company notes that for short periods, forecasts can be off by as much as 30-40 %, which may result in 350 MW of power that has to be quickly balanced in either direction. This involves interaction with all resources in the Nordic electricity market of Denmark, Sweden, Norway, and Germany and selling or buying electricity as needed. On the average day, the upward and downward regulating resources may be called upon as often as 50 times (in a typical calendar year, Demark exports and imports nearly 30% of its overall electricity consumption). With improved forecasting, lead times for other power sources can be increased and price volatilities reduced.

Perhaps the most interesting aspect of the challenge to integrate wind into the Danish system is this: wind power sits at the center of the institutional framework of the electric system and is a key part of the nation’s energy strategy – a nation which is consciously aimed at a goal of 100% self-sufficiency from renewables in the next forty years. In most other countries, wind is considered to be just one of many resources, and a problematic one as well, owing to its intermittency. In Denmark, wind IS the main abundant energy resource. The Danes have been blessed with an enormous wind resource, and with a geographic location that places them between much larger markets (that they can sell to and buy from), as well as huge hydro storage potential to the north. But they have also aggressively and proactively positioned themselves to take advantage of those resources and make the most of them. As a consequence, the Danes have a realistic shot at moving from having wind supply 25% of their electricity to 50% within the next decade. Developing and integrating the second 25% will clearly be harder than the first 25%, and will require considerably more planning, technology, ingenuity, and commitment. The lessons learned from this journey will undoubtedly be of great value to other nations that are just now taking baby steps, and who are smart enough to pay attention to the accomplishments of this small island on the North Sea.